M272 Engine 287 HO M272 (FAH) 10/05/04

Objectives

• identify differences between M112 and M272 • explain the camshaft adjusters operation

• identify major components of the M272 • explain function of the swirl flaps

Contents

Comparison 4

Highlights 6

Motor mechanicals 9 Oil level switch 12 Crankcase ventilation 16 Cylinder head 18 Intake manifold 29 ME 9.7 40 Crank sensor 46 O2 sensors 49

Three way catalytic converters 50

M272 – M112 Comparison

Sparkplugs per cylinder 2 Sparkplugs per cylinder 1

Double ignition coils Coil On Plug Compression Ratio 10.0 : 1 Compression Ratio 10.7 : 1 M112 3.2 litre M272 3.5 litre

180 kW 190 kW 350 Nm Torque Nm power kW M112 M272

Comparison

Red line (Dash) = M112 3 valve

Blue line (solid ) = M272 4 valve 60 80 100 120 140 160 180 200 260 280 300 320 340 360 380 400

New M272 introduced in the new SLK 171

Lets look at some highlights

M272 HighLights

• 3.5 litre displacement

• Counter rotating balance shaft • Stiffer engine with lateral main

bearing attachments

M272 HighLights

• 90 degree V-6

• Two stage Intake manifold • Turbulence flaps in the

intake ports

• ME 9.7 control unit

mounted on top of engine • Electrically assisted

thermostat

• No EGR valve

Motor Mechanicals

• Based off of M112 engine • Bore and Stroke increase

compared to M112

• Die cast aluminum crankcase • Silitec coated cylinder liners

• Starter openings both sides of block • 8 lateral main bearing bolts

• Crankshaft lighter as compared to M112 • Wider main bearings as compared to M112

used to reduce vibration

• Iron coated cast aluminum pistons

Balance shaft, familiar function

Oil sensor, now a switch

• Balance shaft similar to the M112

Oil Level Switch

B40

• Only one pin of the two pin connector used • S43 mounted in oil pan

• Chain driven oil pump

Cylinder head

4 valves

DOHC

Cylinder Head

• New design cast aluminum cylinder heads • 4 overhead camshafts (DOHC)

• 4 valves per cylinder, improve torque and horsepower compared to 3 valve engines

• Camshaft upper bearing surfaces integrated into cam housing cover • Nickel coated high strength

Cylinder Head

• 4 Cam Sensors

• ME can detect Cam position with ignition on

• Intake cam is chain driven and drives exhaust cam via gear

Chain Tensioner

• Step type chain tensioner with internal spring • Located at the lower right front engine

• Must be manually reset if removed • Failure to preset tensioner before

Camshaft Timing Adjusters

adjusters

• Continuously variable

• 40° advanced for intake (from 4° BTDC to up to 36° ATDC)

• 40° retard for exhaust (from 30° BTDC to up to 10° ATDC)

Exhaust Cam Gear

Camshaft Position Sensors

each camshaft

• True Power On (TPO) sensor technology capable of detecting cam position with stationary

engine

• Right and left camshaft signals staggered by 240° camshaft angle

Impulse Wheels

M272 mounted on the front of each camshaft timing adjuster

– Each impulse wheel has a different part number

• The openings of the impulse wheels help ME determine the camshafts exact position

• Can only be used one time!

• If new impulse wheels are not used the pins could shear off causing massive damage to adjusters

Both locating pins sheared off when reinstalled

Gouging of

Exhaust Cam Gear

• Smaller outer gear spring loaded for noise reduction • Gear must be held in place

prior to disassembly • Segment Ring must be

Camshaft Timing Network

B6/4 – Camshaft position sensor (intake left)

B6/6 – Camshaft position sensor (exhaust left)

B6/7 – Camshaft position sensor (exhaust right)

B6/5 – Camshaft position sensor (intake right)

B11/4 – Engine coolant temperature sensor

B70 – Crankshaft hall sensor B2/5 – MAF

N3/10 – ME 9.7

Y49/5 – Camshaft timing control solenoid (exhaust right)

Y49/7 – Camshaft timing control Solenoid (Intake right)

Y49/4 – Camshaft timing control solenoid (intake left)

Y49/6 – Camshaft timing control Solenoid (exhaust left)

Camshaft Position

• Align balancer (305°) to front cover pointer • Check impulse wheels stamped numbers • If above line up properly cam positions

Camshaft Timing Basic Position

to front cover pointer 2. Front cover pointer

3. Upper camshaft marks

4. Camshaft marks aligned to head

1

2

3

Intake

Variable runners

Swirl flaps

Intake Manifold

intake manifold with

integrated vacuum reservoir • Variable intake runner

• Short runner for higher RPM • Long runner for lower RPM • Swirl-Flaps also added

Variable Length Intake Manifold

1750 RPM intake flaps closed (long runner) • Better cylinder filling and increased

torque

• Above 3900 RPM switchover solenoid deactivated via ME intake flaps open (short runner)

• Incoming air follows short runner • Unlike M112, M272 has two diaphragm

actuators

Short runner Long runner Vacuum applied

Swirl Flaps

air is swirled via swirl flap for improved mixture process

• Vacuum diaphragm driven by ME controls flap position

• Swirl flap position sensors (hall sensors) monitor 2 magnets attached to swirl flap actuating shafts to determine flap position (activated/not activated) • Sensors located at rear of intake manifold

Swirl flap position sensors

B28/10 B28/9

Swirl Flap Functional Diagram

12 – Intake manifold 1 – Swirl flap

22/9 – Aneroid capsule swirl flap Switchover

B11/4 – Coolant temperature sensor B70- Crankshaft hall sensor

B28/9 – Left intake manifold swirl flap position sensor

B28/10 – Right intake manifold swirl flap position sensor

B2/5 – Hot film mass airflow sensor M16/6 – Throttle valve actuator N3/10 – ME 9.7

Y22/9 – Intake manifold swirl flap switchover valve

A – Swirl flap recessed (no swirl) B – Swirl flap outward (swirl)

ME 9.7

Inputs

Outputs

ME 9.7

• Cylinder sequential injection • Single spark plug coil

(control and diagnostics)

• Electronic throttle plate positioning • LIN communication with alternator • Turbulence flap regulation

• Variable length intake runner control • After run process

N3/10 – ME 9.7

Note: When erasing DTC’s you must wait for the after run function to finish otherwise faults may remain.

ME After Run Process

• ME performs an after run process when circuit 15 is switched off • After run is determined by ME and required to store inputs

• After run time is typically 5 seconds but can take several

minutes longer depending on various functions (temperature management, OBD, DAS3 etc.)

– at 176°F approx. 4 seconds, at 68°F approx. 60 seconds and at -22°F approx. 150 seconds

ME 9.7 Inputs/Outputs Legend

• A16/1 – Right knock sensor • A16/2 – Left knock sensor

• B2/5 – Hot film mass air flow sensor • B4/3 – Fuel tank pressure sensor

• B6/4 – Left intake camshaft hall sensor • B6/5 – Right intake camshaft hall sensor • B6/6 – Left exhaust camshaft hall sensor • B6/7 – Right exhaust camshaft hall sensor • B11/4 – Coolant temperature sensor

• B28 – Intake manifold pressure sensor • B28/9 – Left intake manifold swirl flap

position sensor

• B28/10 – Right intake manifold swirl flap position sensor

• B37 – Accelerator pedal sensor • B70 – Crankshaft hall sensor • G2 – Alternator

• N10/1 – Driver SAM

• N10/1kR – Circuit 87 relay • N10/1kS – Starter relay • N10/1kO – Air pump relay • N10/2 – Rear SAM

• N10/2kA – Fuel pump relay • S40/3 – Clutch pedal switch • S40/5 – Start enable clutch

pedal switch

• S43 – Oil level check switch • M4/7 – Suction fan

• T1/1-6 – Ignition coils 1 to 6

• Y10/1 – Power steering pump pressure regulator valve

• Y22/6 – Variable intake manifold switchover valve

ME 9.7 Network Signals

N15/5 – Electronic selector lever module control unit A1 – Instrument Cluster N47-5 – ESP and BAS control unit

N80 – Steering column module

Y3/8n4 – Fully integrated transmission control unit X11/4 – Diagnostic connector N93 – Central gateway

control unit

N22 – AAC control and operating unit

N2/7 - Restraint systems control unit

Crank sensor (Hall)

O2 sensors

Three way catalytic converters

Ignition coil

Crank Sensor

• Hall effect sensor (not inductive)

• Output signal switches between ground and 5 volts

• Incremental ring gear 58 teeth (60–2) is carry over

Sensor Signals

A = Recognition of ignition TDC of cylinder 1 - second negative signal edge of crankshaft

hall sensor after the gap - Signals 5 and 6 are "LOW"

- Rpm signal (4) changes from "HIGH“ to "LOW"

1 - Crank angle (CKA)

2 - Ignition TDC cylinder (in firing order) 3 - Signal of crankshaft Hall sensor (B70) 4 - Rpm signal TNA

5 - Camshaft Hall sensor intake signal, left and right 6 - Camshaft hall sensor exhaust signal, left and

O2 Sensors

• Upstream wide-band O2 sensors as known from the M271 and OM648 • Downstream planar type O2 sensors

mounted in catalytic converter housing • Three Way Catalytic Converters (TWC)

Three Way Catalytic Converters

cells each

• Reduces Hydrocarbons (HC) • Reduces Carbon Monoxide (CO) • Reduces Nitrogen Oxides (NOX) • Downstream O2 sensor mounted

O2 Sensor Networking

158 – Catalytic converter

B2/5 – Hot film mass airflow sensor B11/4 – Coolant temperature sensor B70 – Crankshaft hall sensor

B37 – Accelerator pedal sensor G3/3 – Left upstream O2 sensor G3/5 – Left downstream O2 sensor G3/4 – Right upstream O2 sensor G3/6 – Right downstream O2 sensor N3/10 – ME 9.7

Ignition Coil

• Individual coil on plug

• Driver located inside coil not in ME 9.7 • Each coil controlled separately

• Diagnostic information sent back to ME • Bi-directional communication with ME

Pin 1 – batt Pin 2 – ground Pin 3 – ground

Ignition Networking

A16/1 – Right knock sensor A16/2 – Left knock sensor

B37 – Accelerator pedal sensor M16/6 – Throttle valve actuator

Hot Film Mass Airflow Sensor

to ME

• Integrated Intake air temperature sensor used

Temperature management

Thermostat

Temperature Management

via Me 9.7

• 3 plate thermostat

• Regulates temperature from 185°F to 221°F (85°C to 105°C)

• Heating element in thermostat energized to heat thermostat

• 4 operating modes dependent on engine temperature and load

Fuel tank

• Magnesium cover helps protect tank • Two layer steel tank with 18.4

gallon capacity

• In tank fuel supply system operates with 3.8 bar pressure

• Fuel filter with pressure regulator • Returnless fuel system

Fuel Networking

N10/2kA Fuel pump relay

N3/10 ME-SFI control unit 75 Fuel tank

76 Vent valve, except USA 77 Activated charcoal 12 Intake manifold 17 Fuel rail 17/1 Fuel pressure reservoir A Electrical line B Fuel pipe C Purge line

Fuel Pump Control

• Fuel pump controlled via fuel pump relay (N10/2kA)

• Fuel pump Relay located in rear SAM (N10/2)

• Fuel pump relay energized via ME • Fuel pump runs ~ 1 second after

ignition on N10/2 – Rear SAM

Fuel Supply Circuit In Tank

Pressure Regulator (3.8 bar)

Access Point To Fuel Filter and Pump

Fuel Pressure Regulator

Fuel Level Sensor

Splash Bowl

• Gives the customer firmer feel in steering at higher speeds and more assist for parking maneuvers at slower speeds

• ME 9.7 now controls functions of the Speed Sensitive Power Steering system

• The valve port is adjusted for steering support required for the current driving condition and is dependent on the following input signals:

– Engine speed

– Vehicle speed (Via CAN) – Steering angle (Via CAN)

• The pressure regulator valve controls the valve port and is rigidly connected to the power steering pump

• It is actuated according to a performance map with a duty cycle of 10 to 90% and regulates the amount delivered to the power steering pump at between 2 and 9 liters/minute

• The pressure regulator valve is opened wide for ignition ON and during engine start

• In the case of faults on the input signals or on the pressure regulator valve, actuation is interrupted immediately and the maximum support is available from the power steering pump

Speed Sensitive Power Steering

Networking